TRANSPORT OF REACTIVE ANIONS AND CATIONS TRANSPORT OF REACTIVE ANIONS AND CATIONS

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TRANSPORT OF REACTIVE ANIONS AND CATIONS TRANSPORT OF REACTIVE ANIONS AND CATIONS

IN A VOLCANIC SOIL:

EXPERIMENTS AND MODELLING EXPERIMENTS AND MODELLING

Sansoulet J., Sansoulet J.,

Feder F., Simunek, J. Findeling, A., Doelsch, E., Bochu V.

August, 26 2008

University of Technology, Vienna

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Introduction Introduction

Agricultural crop fields are commonly amended with organic products that contain nitrogen and heavy metals, such as rich pig manure, which can lead to soil and groundwater pollution.

Source : Feder F.

Organo- mineral complex

NO₃^-

Volcanic ash soil with variable charges could potentially develops anion and cation exchange capacities which could interact with anions and cations during the transport.

« La Réunion » Island

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Introduction Introduction

Our objectives are :

To study the impacts of a pig manure amendment on the retention and flux of chemical elements – anions and

cations into volcanic ash soil columns

To simulate ions transport with a biogeochemical transfer model (Ca, Na, K, NO3, Cl, Zn, Cu, Mg, Fe, Mg)

→→ The The ability to predict accurately water flow and solute transportability to predict accurately water flow and solute transport into and through a Nitisol is essential for an effective managem

into and through a Nitisol is essential for an effective management of ent of agricultural practices and the control of environmental risks.

agricultural practices and the control of environmental risks.

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Material and Method Material and Method

Over a 120-days period

3 large columns (85 x 40 cm) from a Nitisol : one untreated column (control) and two amended with pig manure

Soil moisture regimes were continuously monitored at four depths and analyzed : Ca, Na, K, NO₃, Cl, Zn, Cu….

Pig manure amendment

Collectors 17.5 cm ^:

Microtensiometers, TDR and

Redox

55 cm :

Redox

30 cm :

Redox

85 cm :

Redox

Datalogger

+ regular amounts of water of 200 mm a week Untreated

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Material and Method Material and Method

HYDRUS-1D.lnk PHREEQC for Windows.lnk This code contains modules simulating :

transient water flow in variably-saturated media Richards equationRichards equation

the transport of multiple components

mixed equilibrium/kinetic biogeochemical reactions

Sorption surfaces based on thermodynamic equilibrium, kinetic, or mixed equilibrium-kinetic reactions

heat transport

HP1 HP1 – – Coupled HYDRUS Coupled HYDRUS - - 1D and PHREEQC model 1D and PHREEQC model

Šimůnek et al. 2006, 2008

Parkhurst & Appelo 1999 Šimůnek et al. 2006

Advection Advection--

dispersion dispersion equations equations

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Material and Method Material and Method

-0.80 -0.75 -0.70 -0.65 -0.60 -0.55 -0.50 -0.45 -0.40 -0.35

We defined :

4 layers with hydraulic (water retention curve and Ksat) and chemical properties (retention and nitrification)

Initial conditions : water and solutes Inputs : pig manure and irrigation

Evaporation

Observations nodes (inverse procedure)

→ Example : Water initial conditions

Pressure head, m

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Results Results

Water balance Water balance

-200 300 800 1300 1800 2300 2800 3300

Storage variation Default Sampled water Evaporation Drainage Water supply

Amount of water (mm)

Column 1 Column 2 Column 3

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Results Results

Inverse procedure

Inverse procedure : : Observed pressures head used as

Observed pressures head used as a part of objective function

a part of objective function

-70 -60 -50 -40 -30 -20 -10 0 10

0 10 20 30 40 50 60

Time, d

Potential, cm

17.5 cm 30 cm 55 cm 80 cm

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Results Results

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

0 10 20 30 40 50 60

Time, days

Cumulated drainage, m

Observed Simulated

Inverse procedure : Inverse procedure :

Observed cumulated drainage used as validation

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Results Results

24 cm

45 cm

65 cm

85 cm 0 cm

1,2 g K⁺ 2,2 g

40 m g 0,5 g

0,46 g

0,4 g 0,3 g

Na⁺ 1,3 g

2 g

1,2 g C a⁺⁺

3,2 g

3 g 1,4 g

24 cm

45 cm

65 cm

85 cm 0 cm

K⁺

0,6 g 0,2 g

40 m g 0,6 g

0,16 g

0,2 g 1 g

1,6 g Na⁺

0,4 g

1 g 1,4 g

2 g C a⁺⁺

0,4 g

0,8 g 24 cm

45 cm

65 cm

85 cm 0 cm

1,2 g K⁺ 2,2 g

40 m g 0,5 g

0,46 g

0,4 g 0,3 g

Na⁺ 1,3 g

2 g

1,2 g C a⁺⁺

3,2 g

3 g 1,4 g 24 cm

45 cm

65 cm

85 cm 0 cm

24 cm

45 cm

65 cm

85 cm 0 cm

24 cm

45 cm

65 cm

85 cm 0 cm

1,2 g K⁺ 2,2 g

40 m g 0,5 g

0,46 g 1,2 g

K⁺ 2,2 g

40 m g 0,5 g

0,46 g

0,4 g 0,3 g

Na⁺ 1,3 g

2 g 0,4 g 0,3 g

Na⁺ 1,3 g

2 g

1,2 g C a⁺⁺

3,2 g

3 g 1,4 g

1,2 g C a⁺⁺

3,2 g

3 g 1,4 g

24 cm

45 cm

65 cm

85 cm 0 cm

K⁺

0,6 g 0,2 g

40 m g 0,6 g

0,16 g

0,2 g 1 g

1,6 g Na⁺

0,4 g

1 g 1,4 g

2 g C a⁺⁺

0,4 g

0,8 g 24 cm

45 cm

65 cm

85 cm 0 cm

24 cm

45 cm

65 cm

85 cm 0 cm

24 cm

45 cm

65 cm

85 cm 0 cm

K⁺

0,6 g 0,2 g

40 m g 0,6 g

0,16 g K⁺

0,6 g 0,2 g

40 m g 0,6 g

0,16 g

0,2 g 1 g

1,6 g Na⁺

0,4 g

0,4 g 0,2 g

1 g

1,6 g Na⁺

0,4 g

1 g 1,4 g

2 g C a⁺⁺

0,4 g

0,8 g 1 g

1,4 g

2 g C a⁺⁺

0,4 g

0,8 g

Calcium and potassium interacted with cation exchange complexe ; sodium were less adsorbed and thus more mobile

Control Amended with pig manure

Retention and fluxes of K

⁺⁺

, Na , Na

⁺⁺

and Ca and Ca

⁺⁺⁺⁺

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Results Results

0.0 0.2 0.4 0.6 0.8 1.0

Na Ca

0.000 0.002 0.004 0.006 0.008 0.010

0.000 0.002 0.004 0.006 0.008 0.010 K

Measured drainage, mmol / L

Simulated drainage, mmol / L

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Results Results

2 4 c m

4 5 c m

6 5 c m

8 5 c m 0 c m

0 ,4 g 0 ,4 g

0 ,7 g

N O₃^- 2 ,3 g

1 ,6 g

0 ,2 g 0 ,4 g

C l^- 1 ,8 g

1 ,6 g

2 4 c m

4 5 c m

6 5 c m

8 5 c m 0 c m

0 ,4 g

N O₃^- 5 0 m g

0 ,4 5 g

0 ,1 g C l^- 0 ,6 g

0 ,7 g 2 4 c m

4 5 c m

6 5 c m

8 5 c m 0 c m

0 ,4 g 0 ,4 g

0 ,7 g

N O₃^- 2 ,3 g

1 ,6 g

0 ,2 g 0 ,4 g

C l^- 1 ,8 g

1 ,6 g 2 4 c m

4 5 c m

6 5 c m

8 5 c m 0 c m

2 4 c m

4 5 c m

6 5 c m

8 5 c m 0 c m

0 ,4 g 0 ,4 g

0 ,7 g

N O₃^- 2 ,3 g

1 ,6 g

0 ,2 g 0 ,4 g

C l^- 1 ,8 g

1 ,6 g 0 ,4 g

0 ,4 g

0 ,7 g

N O₃^- 2 ,3 g

1 ,6 g 0 ,4 g

0 ,4 g

0 ,7 g

N O₃^- 2 ,3 g

1 ,6 g

0 ,2 g 0 ,4 g

C l^- 1 ,8 g

1 ,6 g 0 ,2 g

0 ,4 g C l^- 1 ,8 g

1 ,6 g

2 4 c m

4 5 c m

6 5 c m

8 5 c m 0 c m

0 ,4 g

N O₃^- 5 0 m g

0 ,4 5 g

0 ,1 g C l^- 0 ,6 g

0 ,7 g 2 4 c m

4 5 c m

6 5 c m

8 5 c m 0 c m

2 4 c m

4 5 c m

6 5 c m

8 5 c m 0 c m

0 ,4 g

N O₃^- 5 0 m g

0 ,4 5 g

0 ,1 g C l^- 0 ,6 g

0 ,7 g 0 ,4 g

N O₃^- 5 0 m g

0 ,4 5 g 0 ,4 g

N O₃^- 5 0 m g

0 ,4 5 g

0 ,1 g C l^- 0 ,6 g

0 ,7 g 0 ,1 g

C l^- 0 ,6 g

0 ,7 g

Nitrate also interacted with anion exchange complexe ; chlorides were less adsorbed and thus more mobile

Amended with pig manure Control

Retention and fluxes of NO

₃₃^-^-

and Cl and Cl

^-^-

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Results Results

Measured drainage, mmol / L

Simulated drainage, mmol / L

0.0 0.5 1.0 1.5 2.0 2.5 3.0

NO3 Cl

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Results Results

Difficulties…

Cu and Zn could not transfer in depth :

they could not be decomposed during the experimental period

they did largely interact with the first horizon of the soil

Geochemical model is a somewhat complex with respect to the number components, e.g. all these heavy metals as Cu, Mn, Fe, Zn…so there were convergence problems

→ no possibility to model all the components

Cu Zn

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Conclusion Conclusion

Experimental and modelling results showed that there was an interaction between anions and cations in the soil exchangeable phase.

These results emphasized the specific hydraulic and exchange properties of a volcanic soil under tropical conditions.

These specific features must be taken into account to properly predict the fate of organic matter and inorganic pollutants in the soil and down to the groundwater.

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Thank you for your attention

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Results Results

2 4 c m

4 5 c m

6 5 c m

8 5 c m 0 c m

1 0 9 ,5 m g

C u

1 1 0 m g

0 ,5 m g

3 0 9 m g

Z n

3 1 0 m g

1 m g

2 4 c m

4 5 c m

6 5 c m

8 5 c m 0 c m

Z n

1 m g

C u

1 m g

1 m g 2 4 c m

4 5 c m

6 5 c m

8 5 c m 0 c m

1 0 9 ,5 m g

C u

1 1 0 m g

0 ,5 m g

3 0 9 m g

Z n

3 1 0 m g

1 m g 2 4 c m

4 5 c m

6 5 c m

8 5 c m 0 c m

2 4 c m

4 5 c m

6 5 c m

8 5 c m 0 c m

1 0 9 ,5 m g

C u

1 1 0 m g

0 ,5 m g 1 0 9 ,5 m g 1 0 9 ,5 m g

C u

1 1 0 m g

0 ,5 m g

3 0 9 m g

Z n

3 1 0 m g

1 m g 3 0 9 m g 3 0 9 m g

Z n

3 1 0 m g

1 m g

2 4 c m

4 5 c m

6 5 c m

8 5 c m 0 c m

Z n

1 m g

C u

1 m g

1 m g 2 4 c m

4 5 c m

6 5 c m

8 5 c m 0 c m

2 4 c m

4 5 c m

6 5 c m

8 5 c m 0 c m

Z n

1 m g

Z n

1 m g

C u

1 m g

C u

1 m g

All copper and zinc were adsorbed in the first horizon of the soil

Amended with pig manure Control

Retention and fluxes of Cu

⁺⁺⁺⁺

and Zn and Zn

⁺⁺⁺⁺